Pinworm infections are familiar to parents of young children worldwide. Enterobius vermicularis, commonly known as the pinworm, is parasitic only to humans. Mature worms inhabit the human intestinal tract. However, the female worm ordinarily deposits her eggs in the perianal region and diagnosis of a pinworm infection is usually based on the recovery of the pinworm eggs from this region.
Two types of procedures are commonly used to diagnose pinworm infections. The most reliable diagnostic procedure for finding eggs is to press a strip of cellulose tape on the perianal skin, remove it, and place the tape on a clean microscope slide for examination. The application of adhesive cellulose tape to the perianal region first thing in the morning will usually demonstrate infection.
The second type of diagnostic procedure is the vaseline-paraffin swab. This requires a cotton swab to be dipped in a mixture of vaseline and parawax to thoroughly coat the swab. Such swabs may be stored for long periods if the storage temperature is not such that the vaseline-paraffin on the swab melts. At least four consecutive negative swabs should be obtained before the patient is considered free of infection.
Most laboratories use the cellulose tape method. Generally, the cellulose tape procedure uses a strip of clear cellulose tape, 3/4 inch wide. A piece of tape about four to five inches long is anchored on the underside of a three by one inch slide and smoothed across the top of the slide. A paper label or tab is affixed to the free end of the tape for labeling and identification, and to provide a grip for manipulating the tape.
To collect a sample of pinworm eggs from the perianal area, a wooden tongue depressor or a test tube is held as a support against the back of a slide with cellulose tape affixed to the front of the slide, as described above. The cellulose tape is pulled back from the slide by gripping the label and looping the tape, adhesive side outward, over the support. Pinworm eggs are collected as the sticky tape surface is pressed against the perianal skin.
Once the eggs are collected, the tape is smoothed back into place over the slide, adhesive side down. The patient's name and the date are placed on the label.
Examination of the slide is performed under the low power of a microscope. To make the eggs more visible, the label is gripped and the tape lifted from the slide. A drop of toluene or xylene is placed on the slide, then the tape is smoothed back into position. The toluene or xylene serves to clear the preparation; and under low light intensity, the eggs stand out prominently.
The cellulose tape diagnostic method of the prior art is awkward because it requires the collector to loop the cellulose tape, adhesive side up, over a tongue depressor or test tube. Further, the collector's hands must be adjacent to the perianal area in order to effectively collect eggs while retaining the tape in a fixed position over the support. Thus, the collector exposes his or her hands to infection while collecting the eggs and when the tape is replaced over the slide.